Work gripping and drawing mechanism for sheet shaping machines operating on the forming-by-drawing principle



May 3, 1960 F. ANDERSON WORK GRIPPING AND DRAWING MECHANISM FOR same:

SHAPING MACHINES OPERATING ON THE FORMING-BY-DRAWING PRINCIPLE Original Filed Feb. 8. 1955 8 Sheets-Sheet 1 JH... I r .n l r P l f lfilr p h h b hhh p hh May 3, 1960 F. ANDERSON 2,935,114

WORK GRIPPING AND DRAWING MECHANISM FOR SHEET SHAPING MACHINES OPERATING ON THE FORMING Original Filed Feb. 8. 1955 -BY-DRAWING PRINCIPLE 8 Sheets-Sheet 2 mm QR 8 Sheets-Sheet 3 v F. ANDERSON WORK GRIPPING AND DRAWING MECHANISM FOR SHEET SHAPING MACHINES OPERATING ON THE FORMING-BY-DRAWING PRINCIPLE May 3, 1960 Original Filled Feb. 8. 1955 A Tree/v5 y May 3, 1960 F. ANDERSON 2,935,114

WORK GRIPPING AND DRAWING MECHANISM FOR SHEET SHAPING MACHINES OPERATING ON THE FORMING-BY-DRAWING PRINCIPLE Original Filed Feb. 8, 1955 8 Sheets-Sheet 4 Q x I I t n \l m fw vf/ MI h E HI m \WNNW N Wm i .llll MW QM I m:\. .m W. n1 vmllll Wu n n m uw/E/vroe FPO/{MAN ANDERSON A TTOR/VEY y 1960 F. ANDERSON 2,935,114

WORK GRIPPING AND DRAWING MECHANISM FOR SHEET SHAPING MACHINES OPERATING ON THE FORMING-BY-DRAWING PRINCIPLE Original Filed Feb. 8-, 1955 8 Sheets-Sheet 5 y 1960 F. ANDERSON 2,935,114

WORK GRIPPING AND DRAWING MECHANISM FOR SHEET SHAPING MACHINES OPERATING ON THE FORMING-BY-DRAWING PRINCIPLE Original Filed Feb. 8, 1955 8 Sheets-Sheet 6 May 3, 1960 F. ANDERSON 2,935,114

WORK GRIPPING AND DRAWING MECHANISM FOR SHEET SHAPING MACHINES OPERATING ON THE FORMING-BY-DRAWING PRINCIPLE Original Filed Feb. 8, 1955 8 Sheets-Sheet. 7

ATTOE/VF) y 3, 1960 F. ANDERSON 2,935,114

WORK GRIPPING AND DRAWING MECHANISM FOR SHEET SHAPING MACHINES OPERATING ON THE FORMING-BY-DRAWING PRINCIPLE Original Filed Feb. 8, 1955 B'Sheets-Sheet 8 WORK GRIPPING AND DRAWING MECHANISM FOR SHEET SHAPING MACHINES OPERATING ON THE FORMING-BY-DRAWING PRINCIPLE Frohman Anderson, Las Vegas, Nev.

Original application February 8, 1955, Serial No. 486,773, now Patent No. 2,851,080, dated September 9, 1958. Divided and this application December 24, 1957, Serial No. 704,934

21 Claims. (Cl. 153-32) This application is a division of application Serial No. 486,773, filed February 8, 1955, now Patent No. 2,851,080, which relates to a machine for shaping metal sheets into compound curves by pulling the sheets edgewise from oneend tothe other over a series of forming elements the working faces of which ditfer'in contour transversely of. the'sheets and are disposed in stepped drawing the sheetsthrough the forming structure.

This application relatesv to the last-mentioned component, that is, the pulling mechanism for drawing the work through the sheetforming structure.

The translatable part of the pulling mechanism is moved by theHpower-actuated carriage and includes a draw head with a series of jaws for gripping the leading edge of thesheet, and. a draw arm attached to the reciprocating carriage and coupled to the draw head through a coupling that may includea lost motionfeature to allow a limited motion of the arm relative to the draw head at the beginning and end of each cycle.

The jaws are operated through hydraulic power, being automatically closed at'their pick-up position to grip the sheet and automatically opened to discharge the sheet at the end of thedrawing half cycle.

The gripping elements of the jaws are plates thatslide in converging grooves and are urged forward and back by a hydraulically-operated piston. The jaws are so .mounted that they may be raised and lowered collectively and also individually and they may also be angularly adjusted tobring them into conformity with the elevation and angle of the immediate portion of the edge of the sheet.

The hydraulic system for operating the jaws includes a motor-driven pump and a control valve for selectively connecting the jaw-operating pistons to the high and low pressure sides of the hydraulic system. The control valve is automatically reversed at the end of the movementof the draw head and .jaws in each direction through the instrumentality of limit switches. Alternatively, the reversing of the control valve may be effected through manual switches.

Specifically, the control valve is spring-biased to one position and is moved to the opposite position by a solenoid the energization of which is controlled by the limit switches.

Provision is made to disable a certain number of the jaws on, each end of the series so that the number of 2,935,114 Patented May a, 1960 being drawn. Specifically, this is done through manual shut-off valves, a valve being provided in the hydraulic connection with each of the particular jaws.

The invention comprehends other features of construction and has other objects and advantages as will appear from the following particular description of the embodiment of the invention illustrated in the accompanying drawings, to which reference will now be made.

Fig. l is a side elevation of a complete machine embodying the invention;

Fig. 2 is a plan of the same;

Fig. 3 is a longitudinal section on an enlarged scale of a portion of the forming structure and the draw head taken substantially on the vertical plane of line 33 in Fig. 2;

Fig. 3a is a vertical section on line 3a3a of Fig. 3;

Fig. 4 is a central vertical longitudinal section of a portion of the forming structure on the scale of Fig. 3 and an end elevation of the draw head;

Fig. 5 is a horizontal section of the draw head and of the supporting wing arm and of the associated portion of the draw bench and carriage;

Fig. 6 is a longitudinal vertical section of the draw head taken on line 6-6 of Fig. 5;

Fig. 7 is a detail in perspective of the jaw assembly;

Fig. 8 is a longitudinal central vertical section of the jaw assembly taken on line 8--8 of Fig. 7; g

- Fig. 9 is a transverse section of the jaw assembly taken on line 9 -9 of Fig. 8;

Fig. 10 is a similar section of the same taken on line 10-10 of Fig. 8; s

Fig. 11 is a similar section of the same taken on line 11- 11 of Fig. 8;

Fig. 12 is a detail of the connecting pin of the jaw assembly;

Fig. 13 is a diagram of the jaws and of their operating 1 hydraulic system; a

Fig. 14 is a sectional detail partially in elevation of the control valve for the jaw hydraulic system;

riage s'lidable therein are disposed at one side of the forming structure and the draw arm is attached at one end to the carriage and extends laterally in front of the forming structure.

The forming structure is in the main contained between two uprights and has a rearward extension" which incidentally serves as a supporting table and guide for the work sheets as they are fed into the machine.

The base is of irregular shape and consists of a sub base 11 on the left end of which in respect to the direction of feed are mounted a gear box 12 and the main drive motor 13 and the gear reduction and coupling 14. On the other end of the sub base is mounted a main base 15 a portion of which is shown in Figs. 3 and 4 and which supports the forming structure of the machine.

The two uprights 16 and 17 for the forming structure are secured to the sub base and to the main base which is also contained between the uprights. The forming structure is composed of three stages the first of which has upper and lower elements which cooperate to form a slot the width of which may be varied for different thicknesses of metal and which determines the general path of movement of the work. This first stage imposes a restraint on the sheet and is known as the hold-back stage.

The second stage has a draw-over forming element which is disposed in'front of the first stage, that is, beyond .the first stage in .the direction of draw. The working second stage element is below the slot. so that the-sheet bends down as it emerges from the slot.

The third-stage .forming element is also a draw-over element having a work face of thesame geometrical shape as the second stage element with its working face disposed just beyondthe secondstage element and stepped in relation thereto at an elevationbetween thatof the first and second stage elements. .Thejsheet is drawn over the secondand thirdstage elements ,inrsuch a manner that the two elements engage .theasheet'on opposite sides.

The lower portion of thefirst stage structure cornprises a T-shaped member having a transverse head .18 having a work engaging element 19. secured onits top .face by aclamp 20, and backof the work engaging element is a smoothingplate .21 secured on the head by;a clamp 22. Thecross head :18 is attached: at itsends to secondary uprights'23 and'24 which are interiorly adja-' cent uprights 16 and 17, respectively, and have articulated bearings therein (not shown).

This 'T-shapcd lower memberhasfa rearwardly extending leg 25 which is connected to the pistonof a hydraulic motor 26 throughapivoted crank27-and links 28. The T-shaped lower member is thus given a forwardand back dynamic movement for-reasons notpertinent toithis invention. In this movementthe T-shaped .memberyis supported to slide upon a universallymounted guide;structure 29. I

The upper portion of the first stage or hold-back structure includes .a transversely extending ram 30 which opposes head 18 and element 19 with an upperworkengaging element 31 secured to the ramby clamp 32. Back .is disposed at one side of the formingstructure.

The draw bench structure in the embodiment shown It consists primarily of an elongated stationary channel-shaped bench member 44 which is supported at a mid point on the gear box 12, and serves as a guide for a carriage 45 slidable therein. The bench :44 abuts and is keyed to the upright 16. Elsewhere the bench is supported by legs 46.

On the under far/e of 'thecarriagejis a rack :47 which is engaged by a bull gear 48 in the gear box 12 operatively connected to themotor13. throughreduction gearing in the gear box. The motor is automatically controlled throughmeans notshown, and actuates the bull gear in a maner to reciprocate the. carriage according to operational requirements.

The sheet pulling or drawing mechanism basically comprises a laterallyextendingwing-shaped draw arm 49, which is attached to and reciprocated by the carriage 45, and a draw head 50.carried bythe draw.arm.49 together'with a local :hydraulicsystem including .motor, tank and valve mechanism carriedby: the. arm.

The :wingeshaped. draw .arm'49 comprises .a flat bottom plate'51 which :isfastened at its oneend to thecarriage v45. Eorattachment to the carriage the plate is provided :on its undersideat that:.end .with :1 depending boss 52 :making a thickened portion-which. is of a width to enter between the vertical sides .ofthedraw-bench 44and of a 1 thicknessto-contact the carriagewith the plate just clearingthe .drawbench, as shown in Figs. 1 and 15. This thickened portion of the plate is keyed to the carriage bykeys 53v and is also .boltedto the carriage .as indicated in Fig. 5.

' The :plate .51 is subjected to :the entire pulling force of. the :sheetstandit .is reinforced byea streamlined con- ".cave ;top;.cover:.,sheet T541Whi6hmakes .in efiect a hollow :wing or arm-that extends tacrossinfront ofthe forming mechanism. -.Thel.plate or arm .is.widest .at its attached end and is-rounded on its forward edge-to a:narrower of the element 31 is a smoothing plate 33 which opposes a sheet-S .is fed into .the machineandis lowered;-as the pull begins.

The second stage also includes a ram 37'which has a work engaging element 38 secured on its lowerface and having an upwardly curved work engaging face on its bottom edge which is disposed with its longitudinal center below the exit slot of the first stage. The ram 37 is raised and lowered by toggles connected to a cross bar 39 spanning uprights 16 and 17 and operated by an hydraulic motor 40 (Fig. 2) which is automatically controlled through mechanism not shown. The ram 37 is guided in gibs on the uprights.

The third stage structure has also a T-shaped body member including a cross head 41 and a rearwardly extending leg42. The cross head 41 carries a forming element 43 which opposes the second stage element 38. and has on its upper edge a work engaging face of the same contour as that of the second, stage but slightly higher and in front thereof. The cross head 41 has a longitudinal oil-collecting groove Main its front face whichcommunicates with an oil passage leading to a sump in the base, as shown in Fig. 4. The functioning of these forming elements is fullydescribed inthe saidparent applijustment forward and back through motive power (not shown).

.widthat its free end atwhichgend the. cover sheet 54 steps down in two-steps .-to. a substantially .thinner ,construction. This .free end is supported in its reciprocation by a leg 55..which hasa caster on itssbottom end thatruns .on a rail 56 :flush.withithefoundation.

The plate:51 hasintegrally secured on-its under side .two pairs:of-channel-shaped guides ,for supporting and guiding. a .frame structure thatextends forwardly from .the draw head 50 and. the .f-rametstructure hasa limited freedom of movement. in the guides as willbeseen. One

i.,pair Oflchannel. guides is,numbered 57- and is onthe front edge ofthe plate-extendingforwardly therefrom somewhat nearer'the narrow-endthanthe .:wide end of the plate. This forward extension is enclosed by-suitable .cover plates wwhichinclude anend capjclosure 58 into ..-which the-front extremity of the framereciprocates.

The otherpair of channel guidesj'for the frame are --number.ed 59 (Figs. 3 andi5).an d areatthezrear. edge of plate 51 parallelwithguides'57 but more widely. spaced. Theguide frameof the draw head structure comprises two forwardly converging channel bars.60; and 61 which are attached to the draw head 50 at their-rear ends and come together in a .V-structure. "Thecfiangesof the bars mare Idisposed top and bottom :withthe web outside, and

the top and bottom flanges merge at thejuncture :until the websmeet: and-continue forwardly face to-"face into the cap 58. The framehastwo plates :secured upon its top "facewhichzserve as crossheads guidedin the guides 57 -and'59. The rear plate .62 is relatively wide-and slides in guide'59, suitable bearings 62a,---such as formica. being provided, as indicated by the-stippling in 'Fig.5. The 'forward plate163 is'of arwidth toslide in guides 57-which havesimilar bearings. {Depending from the bottom side of plate 51 iisaan 'abutment block= 64 disposed between plates 62 and 63 and located so that it abuts against the rear. edge of plate 63 on the drawwbut near the end of the .return half of the cycle ibis-free tomove with its supporting plate 51 away from the plate 63 after the jaws ,arrive at the sheet-gripping position. It willbe seen that carriage is stopped and reversed, and then the arm moves forwardly far enough for the block 64 to pick up plate 63 before the draw begins. V f

- The draw head construction 50 will now be described. Attheir rear ends the frame bars 60 and 61 are secured against the forward face of a vertical plate 65 having a vertical rear face 65a which serves as the supporting and adjusting face for the jaw assembly. On the-bottom of plate 65 is secured the'rear edge of a'horizontal plate 66 which has rounded forward corners, as shown in Fig. 5. This plate 66 extends from end to end of plate 65 and underlies and is secured to the bars 60 and 61. A

similar top plate 67 is secured at its rear edge to the top of plate 65 and is also secured on the top flanges of bars 60 and 61. Secured between the forward edges of plates 66 and 67 are vertical plates 68 and 69 whichextend laterally from and aresecured to thewebs of bars .60and 61, respectively. Thusthere is provided an openended housing in front of and mounting the jaw assembly which serves as a truss as well as a housing for hydraulic .manifolds and tubing,

The vertical plate 65 has a series of four. through bolts 70 which pass through vertically elongated holes 71 and screw. into a vertically adjustable jaw holder bar 72 which bears on vertical guide face 65a1 (see Figs. 3 and 6).

On each end of bar 72 is a vertically threaded extension 73 circular in cross-section (see Fig. .4) in which is a manually adjustable screw 74 that bears on its lower end against the top of a rearward extending shoulder member 75 that is secured on each end of plate 65. It will thus be seen that screwingdownon screws 74 will raise the bar 72 and all of the jaws as a unit, while screwing out on thescrews will allow,the bar 72 and the jaws to drop as a unite, The elongated holes 71 permit of such adjustment relative to the plate 65, it beingnecessary to loosen the bolts 70 to release the bar for such adjustment, the bolts being again tightened. after each adjustment. Wrench holes 76 are provided in the bottom plate 66 in registry with each bolt to accommodate the tool for turningthe bolts.

There are shown twelve individual jaws each designated as a whole by the numeral 77. Secured on the top and bottom of the bar 72 are twelve equally spaced screw-retaining plates 78 and 79, respectively, being keyed thereto by keys 80 and 81, respectively, and otherwise secured as by screws (not shown). The plates 78 and 79 are somewhat longer than the width of bar 72 so that their ends extend beyond the rear face of bar 72 and thereby provide a topand bottom longitudinal projection on the rear or supporting faceof bar 72, this face being thus made channel shape with the projections in effect; constituting the flanges for the channel, as shown in Figs. 4 and 6. The grippingmechanism of the jaws is rotatively mounted in a'hub member 82 so as to turn therein on a horizontal axis forthe purpose of adjusting the jaws to the angle of the leading edge of the sheet. The hub member is'shown as circular in cross-section and is vertically tapped to provide a threaded vertical opening therethrough to receive an adjusting screw 83. This adjusting screw has reduced ends which bear in the -oyerhanging extensions of plates 78 and 79, the upper end being slotted fora tdol. Therefore, by turning the screw 15;, the hub 82 and the jaw carried thereby are adjusted ciprocated a piston 88.

Spanning the side plates 85 and 86 and bolted thereto are rearwardly converging top and bottom plates 89 and 90, respectively. As shown, these plates 89 and 90 are set in grooves'in the inner faces of the plates 85 and 86 and form backing members and guides for top and bottom jaws or gripping plates 91 and 92 respectively, the side edges of which occupy the space between the bottoms of the grooves in the side plates and the backing plates. The gripping plates are beveled off and serrated at their ends to enhance their grip upon the edge of the sheet. The side plates have circular cut-outs 93 providing a mouth for the admission of the edge of the sheet.

For actuation the gripping plates are connected by a circular key or coupling member 94 which is seated at its ends in round bores constituting key receiving holes in the gripping plates. This key 94 (Fig. 12) has a diametrical bore 94a which is screw-threaded and receives the reduced threaded end of the piston rod 95. The rear end of the cylinder is closed by a permanent head plug 96 which has aninternal piston ring surrounding the piston rod-9 5, the body-member 84 having a allow of this movement in the side plate grooves.

The body member 84 has a threaded reduced cylindrical axial extension 97 on its forward face which screws into a threaded socket on the hub member 82. The wall of this socket is split, as shownin Fig.9 and is expanded and contracted by a clamping screw 98. The angular position of the jaw may be adjusted when the screw is loosened and it is locked in adjusted position when the screw is tightened.

There are two hydraulic tubes 99 and 100 attached to the body member 84 and communicating with passages in the body member leading to opposite ends of the cylinder. As shown, tube 99 connects with passage 99a leading to the end at the left of piston 88 in Fig. 8 and tube 100 connects with passage 100a leading to the end of the cylinder at the right of the piston in Fig. 8. These tubes 99 and 100 connect with manifolds 101 and 102, respectively, which are housed within the housing in front of vertical plate 65. Two tubes 103 and 164 connect with manifolds 101 and 102, respectively, and are carried by the channel frame structure for the draw head and connect with correspondingly numbered flexible extensions leading to the valve and pump mechanism carried by the arm 49, the flexible portion of the tubing being to allow for the relative movementbetween the arm and the draw head with its guide frame.

The hydraulic pump and valve mechanism is shown particularly in Figs. 5, 13 and 14. It is suspended underneath the plate 51 on a hanger plate 105 that has at its forward end an upstanding arm 106 and 107 on the respective sides with outturned top extension 108 and 109, respectively, that are riveted or bolted to the underside of plate 51. At an intermediate level in front is avalve supporting plate 110; An'extension of plate 105 at the 1y position the jaws to grip the edge of the sheet.

rear end is attached to plate 51 by a bolt 111, suitablespacingmeans (not shown) being, provided.

A..rnotor M,4 is seated on .plate 105 and operates a pump 112 which1 is connected intotank113 which contains the hydraulicfluid.

The valve, designated as .a whole bythe numeral 114,

:is shown in detail in Fig. '14 and is seated upon plate 110. The valve proper has a case 115 and a slidable spool 116. The spool isurged in one directioniby a spring 117 andin the other direction by a solenoid S4. The valve has four ports,.one of which is connected to the pressure side of the pump by tube 118 and another of which is conneetedjto the return to the tank through pipe 119. Qt the other two ports oneis connected to pipe 103 and the other .to pipe ;104. When the spool is in the position at theleft as shown in'Fig. 14 to which it is moved-by the spring, the pressurefluid is connected to tube 103.while tube 104 is connected to the low pressure or return; and .when the spool is moved to the right under theinfluence of the solenoid, the connections to the jaws are reversed, tube 104 being pressure and 103 being return.

trol of the energizationv of the solenoid at controlled "times in the cycle, and may alsobe elfected manually through push buttons connected in parallel to the auto- 'matic controls, as will now be described with especial reference to Fig. 15.

Fig. 16 shows the electrical'circuit for the motor M4 and solenoid S4. Associated with the draw head 50 is an adjustable positive stop member shown as a flat bar 120 '(see especially Fig. '3). This bar is disposed under the flange of an angle bracket 122, the horizontal flange of which is bolted to an arm 123 that is bolted onto the bottom plate 66 and extends forwardly over the bracket.

The bolt 124- which secures the bracket 122 to the arm 123 extends through a slotted opening in the arm to allow of adjustment of the bar 120. Two nuts on the opposite sides of the bracket flange provide for the longitudinal adjustment ofthe bar, and the bar is positioned so that its contact end enters intothe oil groove 41a in the third stage crosshead 41 at the limit of return or pick-up movement of the jaws. The jaw assembly moves very smoothly on the formica bearings and the bar is not subjected to any great impact force, although it serves ,to limit the movement with required exactness and accurate- An adjustable abutment screw 125 in a depending flange on the end of arm 123 bears against the flange of bracket 122 and braces the bracket on impact.

A spring plunger 126 on the end of bar 120 operates a micro limit switch LS7 which is normally closed and is opened by the contact pressure on the plungeragainst the spring. solenoid S4 and spring 117 -moves the valve plunger or spool to theleft in Big. 14 and connects the pressure into line 103 and closes the jaws.

Carried by the wing arm 49 is another limit switch LS8 which is normally open and wat the portion of the cycle near the end olfthe draw this limit switch LS8 strikes a dog 127 adjustable on a bar 128 on the side of the draw bench and closes the circuit of relay 4S which cont ols solenoid S4 and closes the solenoid'cir- This opening of switch -LS7 deenergizes cuit. As will. later be seen, a holding circuit keeps the solenoid energized until the ,switchLS7 ,is again pe d- Th nsr iza ie of s 1enQ d 4cahse th valve plunger to move to the right and connect ,the pressure into line 104 and open. the jaws. I

'To enable manual operation ofrthe jaws the circuit for h r y .4S.. .n d s two PQSh tQn 1. 9am on the outer end of wing @114 Button 129 normally closes its switch contacts which are in series relation toiLS7 andbutton 130is' in normally open relation to the contacts which are in parallel relationto LS8.

Bus bars 131 are laid in the Qinner faces of the upright sides of thedraw bench and brushes '132'are carried by ,continue to run and operate pump 112 until switch 135 is opened.

The energizing of relay 48 will energize the solenoid S4. in the condition shown in Fig. 16 the relay 48 is deenergized and the solenoid S4 is deenergized, leaving spring-117111 control of valve 114 and holding the jaws closed. This is the condition during the draw until the dog-127 engages limit switch LS8 and momentarily closes it. This closes ,the circuit through relay '45 by way of line 136, switchLS7, -'wire138, button 129,wire 139, switch LS8, :and wires and 141 including the relay to line 137. The relay thereupon closes switches 481 and 482. Switch 481 closes the circuit of solenoid S4 through'wire 142,-switch 481 and wire '143 to the other side of the'line through solenoid S4. Normally open switch LS8 reopens at once but relay-switch 4S2 holds the relay circuit closed through-wire 138, wire 144, switch 482, wire 145, wire'140 and wire 141 including relay 48. This condition remains until the holding circuit is brokeneither by the opening of switch LS7 or the opening of the switch controlled by button 129. The closing of the switch controlled by button'130 will also close the circuit for-relay 48.

While the entire twelve jaws will be required for sheets of maximum width, for narrowersheets a lesser number of jaws will be needed and, as shown in Fig. 13, for example, the outer four jaws at each end are provided with shut-elf valves in their connection with the manifolds whereby one or more of .the four may be made inoperative. t

It will belunderstood that the details of the construction of the jaws and their supports and of the particular controls for the operating hydraulic system as shown in the drawings and above particularly described, are merely illustrative of the invention as required by statute, and that other equivalent embodiments will readily occur to those skilled in the art within the scope of the invention as definedin-the following claims.

What is claimed is:

1. A forming-by-drawing machine comprising a .pair

of uprights, -a *formingelement .support spanning the tram .v 2. A'forming-by-drawing machine as defined; in claim 1 in which the abutmennmembers comprised-a block fixed on the plate and a member on the frame sliding and guided by the guides. v

3. A forming-by-drawing machine as defined in claim I. in which. the guides comprise parallel rails on one face of the. wing plate and the frame comprises diverging channel members, together with two spaced cross plates secured thereon and fitting within and slidable upon the guides, the front cross plate constituting one of the abutment members, and in which the other abutment member is a block secured on the said one face of the wing plate between the two cross plates.

4. A forming-by-drawing machine as defined in claim 3 in which the guides are channel members on the bottom face of the wing plate and support the jaw supporting frame guided thereon.

5. In a forming-by-drawing machine having uprights and opposed forming elements therebetween providing a discharge slot for a work piece and a draw bench and a carriage reciprocable therein at one side of the up rights and a wing pla-te extending laterally from the carriage in front of the discharge slot, a draw head carried by the wing plate and comprising a plurality of jaws positionable to engage and grip a work piece emerging from the slot, hydraulic means to open and close the jaws, a valve in control of the hydraulic means, and trip means for actuating the valve operative by movement of the carriage.

6. A draw head as defined in claim 5 in which the hydraulic means comprise a system including a hydraulic pump, two manifolds, a conduit connecting each manifold to each jaw, two conduits, one connected to each manifold, and said control valve having jaws opening and jaw closing positions and operative in alternate positions to connect the high and low pressure sides of the pump reversely to the said two conduits.

7. A draw'head as defined in claim 6 in which the valve includes a spring biasing the plunger in one direction and a solenoid operative on the plunger in opposition to the spring.

8. A draw-head as defined in claim 7 in which the spring biases the valve plunger to a jaw closing position and the solenoid when energized moves the plunger to a jaw opening position;

9. A draw head as defined in claim 7 together with an electric circuit for the solenoid including a control relay, circuit connections for the relay including a normally closed and a normally open switch, trip means engageable with one of the forming elements to open the normally closed switch at the limit of movement of the head toward the forming elements and trip means on the draw bench positioned to engage and close the normally open switch at the conclusion of the draw.

10. In a forming-by-drawing machine having uprights and opposed forming elements therebetween providing a discharge slot for a work piece and a draw bench and a carriage reciprocable therein transversely of the forming elements and a plate carried by the carriage in front of the discharge slot, a draw head carried by the plate and comprising supporting arms, a mounting plate on the arming having a vertical guide face, a jaw holding bar supported upon and guided by said guide face, means to raise and lower the bar relative to said plate, and a pinrality of jaws carried by said holding bar.

11. In a forming-by-drawing machine having uprights and opposed forming elements therebetween providing a discharge slot for a work piece and a draw bench and a carriage reciprocable therein transversely of the forming elements and a plate carried by the carriage in front of the discharge slot, a draw head carried by the plate and comprising supporting arms, a mounting plate on the arms having a vertical guide face, a jaw holding bar supported upon and guided by said guide face, means to raise and lower the bar relative to said plate, a plurality asset 1t of jaws, and individual means for attaching ach 'javi to the holding bar, said individual attaching means in cludingscr'ew means to adjust the jaw vertically relative to the holding bar.

- 12. A draw head as defined in claim 11 inwhich; the holding bar has'a' top and bottom longitudinal projection on its supporting face, together with an attaching hub on each jaw,the hub having a threaded'vertical opening therethrough, and an adjusting screw in said threaded opening having its ends bearing in said projections.

13. A draw head as defined in claim 12 in which the jaw is rotatively adjustable in said hub.

14. In a forming-by-drawing machine having uprights and opposed forming elements therebetween providing a discharge slot for a work piece and a draw bench and a carriage reciprocable therein transversely of the forming elements and a plate carried by the carriage in front of the discharge slot, a draw head carried by the plate and comprising supporting arms, a mounting plate on the arms having a vertical guide face and a bearing arm extending toward the forming elements at each end and having spaced vertical slots therein, a jaw holding bar, headed screws passing through the slots and screwed into the holding bar andadjustably securing the bar to the mounting plate against the said vertical guide face, the bar being of a length to fit it between the bearing arms and having an extension on each end overhanging said arms, adjusting hand screws threaded through said extensions and bearing upon the respective arms, and jaws secured to the rear face of the bar.

15. The draw head construction defined in claim 14 in which the rear face of the holding bar is longitudinally channeled and the jaws have vertically tapped hubs disposed in said channel, together with adjusting screws engaging in the tapped hubs and bearing in the channel flanges.

16. The draw head construction defined in claim 15 in which the jaws are rotatively adjustable in their hubs.

17. In a forming-by-drawing machine, a jaw structure for gripping the leading edge of a work piece to draw it through the forming elements comprising a jaw body having guide grooves converging toward the gripping end, work piece. engaging jaw plates slidable in said grooves with their inner faces angularly disposed and having key receiving holes symmetrically disposed therein intermediate the ends of the plates, a key member extending between the plates and having its ends entered into said holes, the jaw body having an axial cylindrical cavity in its end opposite the gripping end, heads on the ends of the cavity forming a closed cylinder, a piston reciprocable in the cylinder and having a rod connected to said key member, and passages through the body leading to the opposite ends of the cylinder for introducing or relieving pressure therein.

18. A jaw structure as defined in claim 17 in which the grooves are in side plates, together with converging plates attached to the side plates and backing the jaw plates.

19. A jaw structure as'defined in claim 18 in which the key member has its ends beveled to the taper of the grooves and is of a length to permit outward movement of the jaw plates to Work gripping position without interference with the said backing plates, and with a diametrical threaded opening into which the end of the piston rod has threaded engagement.

20. A a jaw structure as defined in claim 17 in whic the end of the jaw body opposite the gripping end has a threaded cylindrical axial extension, together with an attaching hub member having an internally threaded collar extension into which the threaded extension on the jaw body engages.

21. A jaw structure as defined in claim 20 in which the said collar extension is split, together with a clamping screw through the split ends for releasing or applying clamping engagement of the collar about the threaded 

